ASTM D4929-99

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An American National Standard
Designation: D 4929 – 99
Standard Test Methods for
Determination of Organic Chloride Content in Crude Oil
This standard is issued under the fixed designation D 4929; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Techniques to Evaluate Analytical Measurement System
Performance
1.1 These test methods cover the determination of organic
chloride (above 1 μg/g organically-bound chlorine) in crude
3. Summary of Test Methods
oils, using either distillation and sodium biphenyl reduction or
3.1 A crude oil distillation is performed to obtain the
distillation and microcoulometry.
naphtha cut at 204°C (400°F). The distillation method was
1.2 These test methods involve the distillation of crude oil
adapted from Test Method D 86 for the distillation of petro-
test specimens to obtain a naphtha fraction prior to chloride
leum products. The naphtha cut is washed with caustic,
determination. The chloride content of the naphtha fraction of
repeatedly when necessary, until all hydrogen sulfide is re-
the whole crude oil can thereby be obtained. See Section 5
moved. The naphtha cut, free of hydrogen sulfide, is then
regarding potential interferences.
washed with water, repeatedly when necessary, to remove
1.3 Test Method A covers the determination of organic
inorganic halides (chlorides).
chloride in the washed naphtha fraction of crude oil by sodium
3.2 There are two alternative test methods for determination
biphenyl reduction followed by potentiometric titration.
of the organic chloride in the washed naphtha fraction, as
1.4 Test Method B covers the determination of organic
follows.
chloride in the washed naphtha fraction of crude oil by
3.2.1 Test Method A, Sodium Biphenyl Reduction and
oxidative combustion followed by microcoulometric titration.
Potentiometry—The washed naphtha fraction of a crude oil
1.5 This standard does not purport to address all of the
specimen is weighed and transferred to a separatory funnel
safety concerns, if any, associated with its use. It is the
containing sodium biphenyl reagent in toluene. The reagent is
responsibility of the user of this standard to establish appro-
an addition compound of sodium and biphenyl in ethylene
priate safety and health practices and determine the applica-
glycol dimethyl ether. The free radical nature of this reagent
bility of regulatory limitations prior to use.
promotes very rapid conversion of the organic halogen to
1.6 Values expressed in acceptable SI units are to regarded
inorganic halide. In effect this reagent solubilizes metallic
as the standard. The preferred concentration units are micro-
sodium in organic compounds. The excess reagent is decom-
grams of chloride per gram of sample.
posed, the mixture acidified, and the phases separated. The
2. Referenced Documents aqueous phase is evaporated to 25 to 30 mL, acetone is added,
and the solution titrated potentiometrically.
2.1 ASTM Standards:
2 3.2.2 Test Method B, Combustion and Microcoulometry—
D 86 Test Method for Distillation of Petroleum Products
The washed naphtha fraction of a crude oil specimen is injected
D 1193 Specification for Reagent Water
into a flowing stream of gas containing about 80 % oxygen and
D 4057 Practice for Manual Sampling of Petroleum and
20 % inert gas, such as argon, helium, or nitrogen. The gas and
Petroleum Products
sample flow through a combustion tube maintained at about
D 4177 Practice for Automatic Sampling of Petroleum and
800°C. The chlorine is converted to chloride and oxychlorides,
Petroleum Products
which then flow into a titration cell where they react with the
D 6299 Practice for Applying Statistical Quality Assurance
silver ions in the titration cell. The silver ions thus consumed
are coulometrically replaced. The total current required to
replace the silver ions is a measure of the chlorine present in
These test methods are under the jurisdiction of ASTM Committee D-2 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
the injected samples.
D02.03 on Elemental Analysis.
3.2.3 The reaction occurring in the titration cell as chloride
Current edition approved Jan. 10, 1999. Published March 1999. Originally
enters is as follows:
published as D 4929 – 89. Last edition D 4929 – 94.
Annual Book of ASTM Standards, Vol 05.01.
Annual Book of ASTM Standards, Vol 11.01.
4 5
Annual Book of ASTM Standards, Vol 05.02. Annual Book of ASTM Standards, Vol 05.03.
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D 4929
2 1
7.2 Tee Adapter, borosilicate, 75° angle side-arm, 24/40
Cl 1 Ag → AgCl ~s! (1)
ground-glass joints.
3.2.4 The silver ion consumed in the above reaction is
7.3 Thermometer, ASTM thermometer 2C (–5 to 300°C) or
generated coulometrically thus:
2F, (20°F to 580°F).
1 2
Ag° → Ag 1 e (2)
7.3.1 Other temperature measuring devices, such as thermo-
couples or resistance thermometers, may be used when the
3.2.5 These microequivalents of silver are equal to the
temperature reading obtained by these devices is determined to
number of microequivalents of titratable sample ion entering
produce the same naphtha fraction that is obtained when
the titration cell.
mercury-in-glass thermometers are used.
4. Significance and Use 7.4 Thermometer Adapter, borosilicate, 24/40 inner ground-
glass joint.
4.1 Organic chloride species are potentially damaging to
7.5 Liebig Condenser, borosilicate, 300-mm length, 24/40
refinery processes. Hydrochloric acid can be produced in
ground-glass joints.
hydrotreating or reforming reactors and the acid accumulates in
7.6 Vacuum Take-Off Adapter, borosilicate, 105° angle
condensing regions of the refinery. Unexpected concentrations
bend, 24/40 ground-glass joints.
of organic chlorides cannot be effectively neutralized and
7.7 Receiving Cylinder, borosilicate, 250-mL capacity,
damage can result. Organic chlorides are not known to be
24/40 outer ground-glass joint.
naturally present in crude oils and usually result from cleaning
7.8 Wire Clamps, for No. 24 ground-glass joints, stainless
operations at producing sites, pipelines, or tanks. It is important
steel.
for the oil industry to have common methods available for the
7.9 Receiver Flask, for ice bath, 4 L.
determination of organic chlorides in crude oil, particularly
7.10 Copper Tubing, for heat exchanger to cool condenser
when transfer of custody is involved.
water, 6.4-mm outside diameter, 3-m length.
7.11 Electric Heating Mantle, Glas-Col Series 0, 1-L size,
5. Interferences
140-W upper heating element, 380-W lower heating element.
5.1 Test Method A—Other titratable halides will also give a
7.12 Variacs, 2, for temperature control of upper and lower
positive response. These titratable halides include HBr and HI.
heating elements, 120 V, 10 amps.
5.2 Test Method B—Other titratable halides will also give a
positive response. These titratable halides include HBr and HI
8. Reagents and Materials
(HOBr and HOI do not precipitate silver). Since these oxyha-
8.1 Acetone, chloride-free. (Warning: See Note 1.)
lides do not react in the titration cell, approximately 50 %
microequivalent response is detected.
NOTE 1—Warning: Extremely flammable, can cause flash fires. Health
5.2.1 This test method is applicable in the presence of total
hazard.
sulfur concentration of up to 10 000 times the chlorine level.
8.2 Caustic Solution,1 M potassium hydroxide (Warning:
See Note 2.) prepared in distilled/deionized water.
6. Purity of Reagents
NOTE 2—Warning: Can cause severe burns to skin.
6.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
8.3 Distilled/Deionized Water.
all reagents shall conform to the specifications of the Commit-
8.4 Filter Paper, Whatman No. 41 or equivalent.
tee on Analytical Reagents of the American Chemical Society,
8.5 Stopcock Grease.
where such specifications are available. Other grades may be
8.6 Toluene, chloride-free. (Warning: See Note 3.)
used, provided it is first ascertained that the reagent is of
NOTE 3—Warning: Flammable. Health hazard.
sufficiently high purity to permit its use without lessening the
accuracy of the determination.
9. Sampling
6.2 Purity of Water—Unless otherwise indicated, references
9.1 Obtain a test unit in accordance with Practice D 4057 or
to water shall be understood to mean reagent water as defined
D 4177. To preserve volatile components, which are in some
by Type III of Specification D 1193.
samples, do not uncover samples any longer than necessary.
Samples should be analyzed as soon as possible, after taking
DISTILLATION AND CLEANUP PROCEDURE
from bulk supplies, to prevent loss of organic chloride or
contamination due to exposure or contact with sample con-
7. Apparatus
tainer.
7.1 Round-Bottom Boiling Flask, borosilicate, 1 L, single
short neck with 24/40 outer ground-glass joint.
NOTE 4—Warning: Samples that are collected at temperatures below
room temperature may undergo expansion and rupture the container. For
such samples, do not fill the container to the top; leave sufficient air space
above the sample to allow room for expansion.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, Whatman No. 41 has been found satisfactory. An equivalent may be used.
MD. Dow Corning silicone has been found satisfactory.
D 4929
9.2 If the test unit is not used immediately, then thoroughly The caustic wash removes hydrogen sulfide, while the water
mix in its container prior to taking a test specimen. Some test wash removes traces of inorganic chlorides either originally
units can require heating to thoroughly homogenize. present in the crude or from impurities in the caustic solution.
After the washings are complete, filter the naphtha fraction to
NOTE 5—Precaution: When heating is required, care should be taken
remove residual free-standing water. Store the naphtha fraction
so that no organic chloride containing hydrocarbons are lost.
in a clean glass bottle. This naphtha fraction can now be
10. Preparation of Apparatus analyzed for organic chlorides by either sodium biphenyl or
combustion/microcoulometric techniques.
10.1 Clean all glassware by rinsing successively with tolu-
11.3 Measure the density of the crude oil specimen and the
ene and acetone. After completing the rinse, dry the glassware
naphtha fraction by obtaining the mass of 10.0 mL (using a
using a stream of dry nitrogen gas. Obtain and record the
10-mL volumetric flask) of each to the nearest 0.1 g.
masses of the round-bottom flask and receiving cylinder.
Assemble the glass distillation apparatus using stopcock grease
12. Calculation
to seal all joints and wire clamps to prevent loosening of the
12.1 Calculate naphtha fraction as follows:
joints. Adjust the thermometer position within the adapter tee
f 5 M /M (3)
such that the lower end of the capillary is level with the highest
n c
point on the bottom of the inner wall of the adapter tee section
where:
that connects to the condenser.
f 5 mass fraction of naphtha collected,
M 5 mass of naphtha collected, and
NOTE 6—A diagram illustrating the appropriate positioning of the
n
thermometer can be found in Test Method D 86. M 5 mass of crude oil specimen.
c
12.2 Calculate the density as follows:
10.2 Form the copper tubing into a coil to fit inside the
receiver flask, leaving room in the center of the flask for the Density, g/mL 5 m/v (4)
receiving cylinder. With the PVC tubing, connect one end of
where:
the copper coil to the water source, and connect the other end
m 5 mass of sample specimen, g, and
of the coil to the lower fitting of the Liebig condenser cooling
v 5 volume of sample specimen, mL.
jacket. Connect the upper condenser fitting to the water drain.
Fill the receiver flask with an ice/water mixture, and turn on the
TEST METHOD A—SODIUM BIPHENYL
water. Maintain the temperature of the condenser below 10°C.
REDUCTION AND POTENTIOMETRY
13. Apparatus
11. Procedure
13.1 Electrodes: The cleaning and proper care of electrodes
11.1 Add a 500-mL crude oil test specimen to tared round
are critical to the accuracy of this test. Manufacturer’s instruc-
bottom flask. Obtain and record the mass of the crude oil-filled
tions for the care of electrodes shall be followed.
flask to the nearest 0.1 g. Connect the flask to the distillation
13.1.1 Glass, general purpose.
apparatus. Place the heating mantle around the flask, and
support the heating mantle/flask from the bottom. Connect the
NOTE 7—When glass electrodes are in continuous use, weekly cleaning
heating mantle to the variacs. Turn on the variacs and start the
with chrome-sulfuric acid (WARNING: Strong oxidizer; can cause severe
distillation. During the distillation, adjust the variac settings to
burns; recognized carcinogen), or other strongly oxidizing cleaning
solution, is recommended.
give a distillation rate of approximately 5 mL/min. Continue
the distillation until a thermometer reading of 204°C (400°F) is
13.1.2 Silver-Silver Chloride, billet-type.
attained. When the temperature reaches 204°C (400°F), end the
13.2 Titrator, potentiometric. The titrator is equipped with a
distillation by first disconnecting and removing the receiving
5-mL or smaller buret and a magnetic stirring motor.
cylinder. After the receiving cylinder has been removed, turn
14. Reagents and Materials
off the variacs and remove the heating mantle from the flask.
Obtain and record the mass of the receiving cylinder and
14.1 Acetone, chloride-free. (Warning: See Note 1.)
distillate.
14.2 Congo Red Paper.
11.1.1 The precision and bias statements were determined
14.3 2,2,4, trimethyl pentane (isooctane), reagent grade.
using mercury-in-glass thermometers only. Therefore, when
(Warning: See Note 3.)
alternate temperature measuring devices are used, the cut-off
14.4 Nitric Acid (Warning: See Note 8.), approximately 5
temperature so obtained shall be that which will produce a
M. Add 160 mL of concentrated nitric acid to about 200 mL of
naphtha cut similar to what would be yielded when mercury-
water and dilute to 500 mL.
in-glass thermometers are used. Such alternate temperature
NOTE 8
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